Underwater Spiders

Diving bell spider

Photo of a diving bell spider by Dr Stefan Hetz.

Professor Roger Seymour (School of Earth & Environmental Sciences, University of Adelaide) and Dr Stefan Hetz (Institute for Biology, Humboldt University) have provided new insights into the lives of diving bell spiders (Argyroneta aquatica), which are air-breathing spiders that spend the majority of their lives underwater.  The researchers’ study revealed that the spiders trap air in dome-shaped webs they build between aquatic plants.  These bubbles act as gills, extracting oxygen from the water and providing enough air for the spiders to breathe for more than 24 hours.  The spiders come up to the surface about once a day to supplement their air supply.

Up until now, scientists did not know how long the spiders stayed under water or how they used the diving bells to breathe.

According to Seymour:

Previous research had suggested the spiders had to come to the surface as often as every 20–40 minutes throughout the day.  Instead, we found that the spiders could sit still for long periods of time, continuing to use their diving bells to extract oxygen even from the most stagnant water on a hot day. Being able to stay still for so long – without having to go to the surface to renew the air bubble – protects the spiders from predators and also keeps them hidden from potential prey that come near.

Each spider constructs a net of silk in vegetation beneath the surface and fills it with air carried down on its abdomen and rear legs.  The spiders spend their entire lives submerged and even lay their eggs in their diving bells.  They are fascinating creatures but unfortunately they are becoming increasingly rare in Europe.

Seymour and Hetz’s findings will be published in The Journal of Experimental Biology.

Diving bell spider

Photo of a diving bell spider by Dr Stefan Hetz.